The present invention relates to granular detergent compositions which are free from deterioration of the powder properties thereof during transport and/or storage and manifest satisfactory easiness in rinsing at the time of use thereof.
It is very important to provide satisfactory easiness in rinsing of heavy duty detergents because it shortens the washing cycle and also renders it possible to economize on electric power as well as rinsing water. As the conventional means for improving the easiness in rinsing with respect to granular heavy duty detergents, there are known the art of adding soap, the art of adding silicone and/or wax, and so forth (cf. Japanese Unexamined Patent Publication No. 113504/1975 and Japanese Unexamined Patent Publication No. 157403/1975). However, the art of adding soap is not an art which promises sufficient improvement of the easiness in rinsing, and the art of adding silicone and/or wax is defective in that said silicone and/or wax adheres to the washed clothes because of their water insolubility.
It is common knowledge that nonionic surface active agents having poly(oxyethylene) chains and/or poly(oxypropylene) chains in their molecules possess low foamability. Accordingly, it can be expected that a granular detergent capable of manifesting satisfactory easiness in rinsing can be obtained by the use of nonionic surface active agents of this kind. On the other hand, granular detergents comprising such nonionic surface active agents as active ingredient are defective in that it is difficult to maintain the fluidity thereof over a long period of time and the detergent grains cake due to moisture absorption and/or compression during shipping and/or storage. In this connection, Japanese Patent Publication No. 10166/1963 discloses a granular detergent comprising poly(oxyethylene)-poly(oxypropylene) alkyl ether combined with polyphosphates which exert a favorable influence on the powder properties of granular detergents, but even this granular detergent exhibits caking due to moisture absortion and/or compression. Under such circumstances, there have hitherto been made several proposals with a view to improving the powder properties of such granular detergents comprising nonionic surface active agents as active ingredient. For instance, in Japanese Patent Publication No. 20634/1972 there is disclosed the art of mixing tripolyphosphate subjected to prehydration in granular detergents. In Japanese Unexamined Patent Publication No. 41612/1977 and Japanese Unexamined Patent Publication No. 41613/1977 there is taught the art of adding a reaction product between high-molecular ethoxylates or high-molecular polyalkylene glycols and acid anhydrides to granular detergents as an anti-caking agent.